Figure 2.

A macrophage invading the basement membrane tube surrounding the myelinated fiber. A cross section of a sural nerve biopsy specimen obtained from a patient with AIDP. A macrophage whose nucleus is indicated by a black asterisk is invading the basement membrane tube that normally surrounds myelinated fibers. Along with the invasion into the basement membrane tube, the cytoplasm of macrophages apposed to myelin initiates degradation of myelin (white asterisks). Note that the cytoplasm of this macrophage located outside the basement membrane tube does not contain myelin debris. A high-powered view of the region in the box in (A) is shown in (B). Basement membranes surrounding myelinated fibers are indicated by arrowheads. Uranyl acetate and lead citrate staining. Scale bars = 2 μm (A) and 0.5 μm (B).